The peripheral end organs for gustation are taste buds, which transduce information on the quality and concentration of chemical taste stimuli into a coded pattern of activity in postsynaptic afferent nerve fibers. In most neurons, transmitter release at presynaptic terminals is dependent upon voltage-gated calcium channels (VGCCs). Some taste stimuli are known to cause depolarization of taste cell membranes followed by Ca++ entry. Other stimuli apparently do not lead to membrane voltage changes. The goal of this new research program is to begin to address these critical last steps of information processing in taste receptor cells. Specifically, we propose to analyze voltage-gated calcium channels in taste cells. These channels are critical for the function of most neuronal synapses but have not been examined systematically in mammalian taste cells. The Specific Aims for the proposed research are: 1) To determine the molecular identities of voltage gated calcium channels present in taste buds. This aim will be carried out using reverse transcriptase-polymerase chain reaction (RT-PCR) on a mixed population of mouse taste buds isolated from circumvallate, foliate and fungiform papillae and the palate. Primer pairs used will be specific for each of the 10 known calcium channel alpha1 subunits (which form the channel pore and determine major functional properties) and for accessory beta, gamma and alpha2-delta subunits, all of which alter important functional properties, including sites for modulation by second messengers. 2) To determine whether the calcium channel types identified in Aim 1 correlate with taste specificities. We will search for co-localization of alpha1 subunits with key proteins involved in taste transduction. 3) To image voltage-gated calcium channel activity in taste receptor cells and determine if channel function is subject to modulation by second messengers relevant in taste transduction. Through these aims, we hope to gain a novel perspective on voltage-gated calcium channels, which play critical roles in all neuronal systems, but have been minimally studied in taste cells to date.